docs: def relation_set(relation_id=None, relation_settings=None, **kwargs):
      """Attempt to use leader-set if supported in the current version of Juju,
      otherwise falls back on relation-set.
  
      Note that we only attempt to use leader-set if the provided relation_id is
      a peer relation id or no relation id is provided (in which case we assume
      we are within the peer relation context).
      """
      try:
          if relation_id in relation_ids('cluster'):
              return leader_set(settings=relation_settings, **kwargs)
          else:
              raise NotImplementedError
      except NotImplementedError:
          return _relation_set(relation_id=relation_id,
                               relation_settings=relation_settings, **kwargs)